Volume 27, 108

Tropical Grasslands (1993) Volume 27, 108–113

Effects of growth stage and sward structure of Macroptilium lathyroides and M. atropurpureum on selective grazing and bite size in goats

Y. NAKANISHP¹, K. TSURU², T. BUNGO, M. SHIMOJO, Y. MASUDA and I. GOTO

Department of Animal Science, Faculty of Agriculture, Kyushu University, Fukuoka, Japan
¹Present address: Kuju Agricultural Research Center, Kyushu University, Kuju-cho, Oita, Japan
²Present address: Fujitsu Co., LTD, Kumamoto, Japan

Abstract

This study was conducted to investigate the effects of growth stage (26, 49, 63, 78 and 106 days of regrowth) and sward structure of phasey bean (Macroptilium lathyroides) and siratro (M. atropurpureum) on selective grazing and bite size of oesophageal fistulated goats. The selectively grazed parts of phasey bean and siratro had higher levels of leaf, crude protein, in vitro dry matter digestibility (IVDMD) and digestible energy (DE) and lower levels of cell wall components than the residual forage. There was more selection when grazing phasey bean than siratro. As plants matured, leaf percentage of the grazed phasey bean decreased but changes in siratro were small. Goats grazing phasey bean had the largest bite size when grazing the 106 day regrowth, whereas animals grazing siratro had the largest bite size when grazing the 63 day regrowth. Bite size of goats grazing phasey bean and siratro was positively correlated with sward height, stem length and dry matter yield, and a higher correlation was found for phasey bean than for siratro. However, the relation between the leaf percentage in the grazed layer of the sward and bite size was inconsistent between the two legumes.